Hello experienced font designers.
I want to insert multiphonics into the Finale score, however, inserting as pictures seems to be a bit awkward. Now I am thinking to make symbols for each multiphonic so that they can be typed as Expression.
What is the best way (perhaps the quickest) to use a png picture (as one attached), to convert it into a vector graphic and than into a font?

If the PNG is sufficiently high resolution, I would use Inkscape’s image tracer to vectorize it, then you can either save as SVG or EPS and import those curves directly into FontForge into any character slot. Once you’ve got all the variants you need, then exporting as a font should be easy (or you can send me the source file and I can create the binary font, if you’d prefer).